The present invention relates to devices for feeding Otto cycle engines with lean combustible mixtures.
It is known to feed air-fuel mixture from the carburettor to the cylinders of a multicylinder spark ignition engine through an induction manifold and through a heat exchanger, in which the mixture is preheated by hot engine exhaust gases, interposed between the mixture outlet of the carburettor and the induction manifold. The use of a heat exchanger in such devices makes it possible to use lean mixtures whilst the engine is running at speed, in order to reduce the amount of atmospheric pollution by the engine exhaust gases. Such devices do not, however, resolve the problems associated with the use of lean mixtures, particularly on cold-starting and the successive transitionary phase of cold-running of the engine.
An object of the present invention is to provide a lean mixture feeding device which avoids the aforesaid problems.